Determination of the yield of radiation-induced peroxidation of sodium linoleate in aqueous monomeric and micellar solutions

Peroxidation of polyunsaturated fatty acids such as linoleic acid in aqueou s micellar solution proceeds through a free-radical chain mechanism and is accompanied by the formation of conjugated dienes, some in the form of hydr operoxides. In the course of an investigation of radiation-induced oxidatio n of aqueous sodium linoleate, we have measured three indexes of peroxidati on-conjugated dienes, hydroperoxides and thiobarbituric acid-reactive subst ances-by means of absorption spectroscopy, high-pressure liquid chromatogra phy and spectrofluorimetry, respectively. There are linear correlations bet ween the amounts of conjugated dienes, hydroperoxides and thiobarbituric ac id-reactive substances. The radiolytic yields have been determined from the radiation dose dependence of the three markers of peroxidation as a functi on of sodium linoleate concentration. The results obtained indicate a stron g effect of the concentrations of oxygen and linoleate on the yields of the products. The yields at different lipid concentrations display a large inc rease in chain propagation length; this is discussed in terms of the effect of micellar size. (C) 1998 by Radiation Research Society.